Materials Data on Na2Gd2MgSi4(O6F)2 by Materials Project

Abstract

Na2MgGd2Si4(O6F)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Na1+ is bonded in a 7-coordinate geometry to six O2- and one F1- atom. There are a spread of Na–O bond distances ranging from 2.41–2.99 Å. The Na–F bond length is 2.33 Å. Mg2+ is bonded to four O2- and two equivalent F1- atoms to form MgO4F2 octahedra that share corners with four SiO4 tetrahedra. All Mg–O bond lengths are 2.11 Å. Both Mg–F bond lengths are 1.99 Å. Gd3+ is bonded in a 7-coordinate geometry to six O2- and two equivalent F1- atoms. There are a spread of Gd–O bond distances ranging from 2.29–2.91 Å. Both Gd–F bond lengths are 2.50 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one MgO4F2 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Si–O bond distances ranging from 1.62–1.69 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one MgO4F2 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Gd3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Mg2+, one Gd3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Na1+, one Gd3+, and two Si4+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Gd3+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Na1+ and two Si4+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Mg2+, one Gd3+, and one Si4+ atom. F1- is bonded in a 4-coordinate geometry to one Na1+, one Mg2+, and two equivalent Gd3+ atoms.